In a prior art injection molding machine, clamp plates are fixed to the surfaces of a pair of platens, a plurality of magnetism generating devices that generate magnetism are installed to the clamp plates for attracting molds to the clamp plates, a pair of molds (a fixed mold and a movable mold) are fixed to the pair of platens by the magnetism generated by these devices, and the movable platen is driven to shift in the direction to approach toward or recede from the fixed platen, and thereby clamping together or separation of the pair of molds is performed. In the state in which the pair of molds are clamped together, synthetic resin in the molten state is injected into a cavity defined between these molds in their interior, and thereby an injection molded product is formed; and thereafter the pair of molds are separated to open them, and the injection molded product is ejected by an ejection mechanism.
Here, in a horizontal type injection molding machine, sometimes shock force operates on the mold, for example during opening of the mold or particularly during ejection for extraction of the injection molded product or the like, and there is a concern of the mold falling off due to this shock force momentarily exceeding the magnetism produced by the magnetism generating devices of the clamp plate. In order to solve these problems, a mold falling prevention device has been proposed in Patent Document #1.
In the mold falling prevention device of Patent Document #1, a bottom edge support device and an upper edge support device are respectively engaged into T shaped grooves that are formed at the lower portion and at the upper portion of a clamp plate that is fixed to the platen of the injection molding machine, and the bottom edge of the mold is supported by a support portion of the bottom edge support device. Moreover, the upper edge of the mold is restricted by a L shaped engagement portion of the upper edge support device so that it cannot come away from (i.e. recede from) the mold fixing surface.
In the mold falling prevention device described in Patent Document #2, at four locations on a contacting surface where a clamp plate (a mold mounting plate) to which a plurality of magnetism generating devices are installed and a mold are contacted together, four key grooves on each side of the contacting surface are formed to be concave and so as to face one another and to communicate together, four key fitting holes are defined by the key grooves of the mold and the clamp plate thus facing one another, and the clamp plate and the mold are integrally connected together by four key members being inserted into and fitted into these four key fitting holes.
And, in the mold falling prevention device described in Patent Document #3, the mold is prevented from falling off by a base block being fixed to a top portion of the clamp plate and one end of a chain member being linked to a link portion of this base block with the position of the link being variable, and by a hook at the other end of the chain member being linked to a U shaped supported member that is formed on the mold.